It is necessary to continually evaluate the hazards, to personnel, from potentially harmful emissions of ultraviolet radiant energy in industrial occupational conditions where sources, such as high intensity electrical gas discharge lamps, arc welders and high-intensity incadescent lamps exist. The patent to Adler et al U.S. Pat. No. 3,851,970, discloses one such monitoring device.
It has been determined that the eyes and skin are not sensitive equally to all wavelengths of ultraviolet light. The American Conference of Governmental Industrial Hygienists has established a curve corresponding to the sensitivity of the eyes and skin to various wavelengths of ultraviolet radiation.
Systems are known which, when calibrated, can measure ultraviolet radiation in a narrow wavelength band. One such device is a spectro radiometer.
To monitor ultraviolet radiation simultaneously over a broad wavelength band, such as 230-320 nanometers, would require many such systems each calibrated to its own narrow wavelength band. Also some sequential system could be used.
The use of about 20 such systems to cover the 230 to 320 nanometer band would be very costly.
There is no known sequential system which would adequately monitor all of the wavelength bands in a rapidly changing ultraviolet radiation field.
Another system which has been proposed for ultraviolet radiation hazards monitoring includes input optics, a prism or grating spectrograph with a mask, shaped to the particular biolobical effects to be evaluated, together with a detector, readout electronics and power supply.
Since the ACGIH curve falls off rapidly in the region between 290 and 320 nm by a factor of about 10.sup.4, it is difficult to provide a mask to perform this function. Also a mask used alone will not provide adequate sideband rejection in an ultraviolet personnel hazard monitor. The units that irradiance measurements adjusted to the photobiological response curve are indicated in are effective radiance units in .mu.W/cm.sup.2.